28 November. Of London’s dead landscapes, there are few like the Heygate Estate, ruin on a Martin scale. A dizzying sprawl of concrete in Southwark, a raised town, great corridored blocks, walkways over communal gardens. Slabs of buildingness. It’s all but empty. It’s to be demolished. Even were it not stuffed with asbestos, it would take a long time.

Laura Oldfield Ford leads the way. Don’t call her a psychogeographer. Many do, and she abjures it. The term’s travelled a long way from its origins as a radical French research program to reconfigure urban space. It cross-fertilised with the tradition of London visionary writing, tangled up with urban invocation. Now it’s a local cliché. A lazy label for hip decay tourism.

Ford, not twee, frequents wreckage. An excoriating critic of neoliberalism and its banalisation of space, she reconfigures her long London walks into raging, celebrated post-punk art. ‘I wanted to take the term psycheography but I wanted it to be about the radicalism of it, not this kind of... leylines and all that,’ she withers. Past the graves of shops, the long, long-shuttered front of what was once Institute of Traditional Karate-Do and Performing Arts. You could follow her with your eyes closed, so loud are her steps.

Through lagoons of drifting late autumn leaves in the shadow of the Heygate enormities. In a very few place is proof of life. A nicknack and net curtains in a window, a car below. Someone’s maintaining a small vegetable garden. There’s graffiti, but not so much as you might think.

In a clearing between benches and the remains of a playground, young men conclave. It’s startling to see anyone after so long alone. It’s an affront not to have the whole world to ourselves. But then they set off. In ragged line. They accelerate, vaulting, along walls, bouncing one by one from brick detail to concrete outcrop, up onto low roofs, over and under flaking-painted barriers, watched by pigeons.

They’re training in parkour, another French import. Psychogeography of the limbs, filtered through Kung Fu movies. No number of ads, music videos, station idents featuring roof-bounding like this can make what we’re watching boring, can alter the fact that watching the parkouristes lurch in ways architects never intended along the buildings’ innards is quite beautiful. There’s salvage. A tough ruin ballet.